Introduction

To monitor the evolution of pH in the northwestern Mediterranean sea, a seaFET sensor has been installed on the EOL buoy in the Bay of Villefranche-Sur-Mer (France) to get continous measurements of pH in addition to the discrete measurements of \(A_\mathrm{T}\) and \(C_\mathrm{T}\) (until October 2015) and spectrophotometric pH.

Material and methods

Continuous measurements

The seaFET sensor #007 was bought from Satlantic (Canada). It was deployed at 2 m depth on a holder underneath the EOL buoy on 18 December 2013. The sensor was set on periodic mode with a frequency of pH measurement (total scale) of 1 hour and a burst size of 10. Every two months, the sensor is brought back to the lab, the data downloaded, the batteries checked and changed if needed and the sensor is re-deployed in the field the same day when possible. Since September 11th 2018, a brand new seaFET #1005 with a new software (V2) was deployed on EOL. Only the sample frequency was set to 3600 sec, burst is no more set.

Discrete sampling

First discrete sampling for \(A_\mathrm{T}\) and \(C_\mathrm{T}\) started on 2014-07-16. We decided to stop the weekly \(A_\mathrm{T}\) and \(C_\mathrm{T}\) sampling on 2015-10-15. For calculation of pH (total scale), we use salinity, \(C_\mathrm{T}\), \(A_\mathrm{T}\) and nutrient correction (Silicate and phosphate) from Point B. We saw that the annual range of \(A_\mathrm{T}\) do not affect the pH calculation. However, we still continue to sample for spectrophotometric pH. As a result:

  • the file containing the discrete data is now spectro.csv (it used to be intercomparaison_spectro_calc_seafet.csv).
  • the script seafet_pointB_report_XXXX.Rmd has been simplified: all figures that used \(C_\mathrm{T}\) and \(A_\mathrm{T}\) data taken at the vicinity of the sensor and measured at LOV or at SNAPO-CO2 are now omitted. Only pH spectro (total scale) discrete samples were kept.

Samples were collected by Alliouane Samir (noted below if different) from 2 m depth using a 6 L Niskin bottle in the vicinity of the pH sensor and at the same moment of a measurement (+/- 15 min). pH samples were transferred to a 500 ml borosilicate glass bottle avoiding any bubble and with overflowing. They are directly measured at lab, spectrophotometrically in 10 cm path length quartz cells (Hellma Analytics, Germany) with a spectrophotometer (USB2000+, Ocean optics, USA) and using a dye (meta Cresol purified dye, University of South Florida). Spectrophotometric pH is measured according to Dickson et al. (2007). Since November 2017, the spectrophotometer was changed by a Cary60 (Agilent technologies).

Calculations of the carbonate system parameters were performed using the R package 3.2.11 (Lavigne & Gattuso, 2011).

Exemple of calculation using the “carb” function: carb(15, \(A_\mathrm{T}\), \(C_\mathrm{T}\), S=Salinity, T=Temperature, P=0, Pt=Phosphate, Sit=Silicate,k1k2=“x”, kf=“x”, ks=“d”, pHscale=“T”, b=“l10”).

Discrete sampling dates

Following are the sampling dates and times (in UTC) of discrete samples at the vicinity of the sensor in EOL buoy:

  • 2018-09-17: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-06-19: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-06-12: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-06-04: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-05-29: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-05-22: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-05-14: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-05-07: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-05-02: sampling spectro pH for lab at 08:00.
  • 2018-04-24: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-04-17: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-04-04: sampling spectro pH for lab at 07:00 (Point B team).
  • 2018-03-27: sampling spectro pH for lab at 07:00 (Point B) and 08:00.
  • 2018-03-20: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-03-14: sampling spectro pH for lab at 09:00 (Point B team).
  • 2018-03-07: sampling spectro pH for lab at 09:00 (Point B team).
  • 2018-02-27: sampling spectro pH for lab at 09:00 (Point B team).
  • 2018-02-19: sampling spectro pH for lab at 09:00 (Point B team).
  • 2018-02-13: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-02-06: sampling spectro pH for lab at 09:00 (Point B team).
  • 2018-01-30: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-01-23: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-01-18: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-01-10: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-01-03: sampling spectro pH for lab at 08:00 (Point B team).
  • 2018-01-02: sampling spectro pH for lab at 10:00 (Point B team).
  • 2017-12-19: sampling spectro pH for lab at 08:00 (Point B team).
  • 2017-12-13: sampling spectro pH for lab at 08:00 (Point B team).
  • 2017-12-04: sampling spectro pH for lab at 08:00 (Point B team).
  • 2017-11-30: sampling spectro pH for lab at 09:00.
  • 2017-09-15: sampling spectro pH for lab at 08:00.
  • 2017-08-29: sampling spectro pH for lab at 08:00.
  • 2017-06-14: pH spectro was not measured because of the lack of data this day.
  • 2017-05-02: sampling spectro pH for lab at 07:00.
  • 2017-03-22: sampling spectro pH for lab at 07:00.
  • 2017-02-01: sampling spectro pH for lab at 07:00.
  • 2017-01-31: sampling spectro pH for lab at 08:00.
  • 2017-01-24: sampling spectro pH for lab at 08:00.
  • 2017-01-17: sampling spectro pH for lab at 08:00.
  • 2017-01-10: sampling spectro pH for lab at 08:00.
  • 2017-01-03: sampling spectro pH for lab at 08:00.
  • 2016-12-21: sampling spectro pH for lab at 09:00.
  • 2016-12-13: sampling spectro pH for lab at 09:00.
  • 2016-12-07: sampling spectro pH for lab at 09:00.
  • 2016-11-08: sampling spectro pH for lab at 09:00.
  • 2016-11-02: sampling spectro pH for lab at 08:00.
  • 2016-10-26: sampling spectro pH for lab at 08:00.
  • 2016-10-18: sampling spectro pH for lab at 07:00.
  • 2016-10-11: sampling spectro pH for lab at 07:00.
  • 2016-10-04: sampling spectro pH for lab at 08:00.
  • 2016-09-27: sampling spectro pH for lab at 07:00.
  • 2016-09-20: sampling spectro pH for lab at 08:00 (done by Point B team, measured the 2016-09-27).
  • 2016-09-13: sampling spectro pH for lab at 08:00 (done by Point B team, measured the 2016-09-27).
  • 2016-09-06: sampling spectro pH for lab at 08:00.
  • 2016-08-31: sampling spectro pH for lab at 07:00.
  • 2016-08-23: sampling spectro pH for lab at 07:00.
  • 2016-08-16: sampling spectro pH for lab at 07:00 (done by Point B team, measured the 2016-08-17).
  • 2016-08-02: sampling spectro pH for lab at 09:00 (done by Point B team, measured the 2016-08-17).
  • 2016-07-26: sampling spectro pH for lab at 07:00 (done by Point B team, measured the 2016-08-17).
  • 2016-07-19: sampling spectro pH for lab at 07:00.
  • 2016-07-12: sampling spectro pH for lab at 08:00.
  • 2016-07-06: sampling spectro pH for lab at 09:00.
  • 2016-07-05: sampling spectro pH for lab at 06:00.
  • 2016-06-28: sampling spectro pH for lab at 07:00.
  • 2016-06-21: sampling spectro pH for lab at 07:00.
  • 2016-06-14: sampling spectro pH for lab at 07:00.
  • 2016-06-07: sampling spectro pH for lab at 07:00.
  • 2016-06-03: sampling spectro pH for lab at 07:00.
  • 2016-06-01: sampling spectro pH for lab at 07:00.
  • 2016-05-24: sampling spectro pH for lab at 07:00 (done by Point B team).
  • 2016-05-17: sampling spectro pH for lab at 07:00.
  • 2016-05-10: sampling spectro pH for lab at 07:00.
  • 2016-05-03: sampling spectro pH for lab at 07:00.
  • 2016-04-25: sampling spectro pH for lab at 08:00.
  • 2016-04-19: sampling spectro pH for lab at 07:00.
  • 2016-04-12: sampling spectro pH for lab at 07:00.
  • 2016-04-05: sampling spectro pH for lab at 07:00.
  • 2016-03-29: sampling spectro pH for lab at 06:00.
  • 2016-03-22: sampling spectro pH for lab at 08:00 (done by Point B team).
  • 2016-03-15: sampling spectro pH for lab at 08:00 (done by Point B team).
  • 2016-03-08: sampling spectro pH for lab at 10:00.
  • 2016-03-01: sampling spectro pH for lab at 09:00.
  • 2016-02-23: sampling spectro pH for lab at 08:00 (done by Point B team).
  • 2016-02-16: sampling spectro pH for lab at 08:00 (done by Point B team).
  • 2016-02-09: sampling spectro pH for lab at 09:00.
  • 2016-02-02: sampling spectro pH for lab at 09:00 (done by Point B team).
  • 2016-01-26: sampling spectro pH for lab at 08:00.
  • 2016-01-19: sampling spectro pH for lab at 08:00.
  • 2016-01-05: sampling spectro pH for lab at 09:00.
  • 2015-12-22: sampling spectro pH for lab at 09:00 (done by Point B team).
  • 2015-12-15: sampling spectro pH for lab at 09:00.
  • 2015-12-08: sampling spectro pH for lab at 09:00.
  • 2015-11-24: sampling spectro pH for lab at 09:30
  • 2015-11-17: sampling spectro pH for lab at 09:30 (done by Point B team).
  • 2015-11-10: sampling spectro pH for lab at 09:30 (done by Point B team).
  • 2015-11-03: sampling spectro pH for lab at 09:30 (done by Point B team).
  • 2015-10-27: sampling spectro pH for lab at 09:00.
  • 2015-10-20: sampling spectro pH for lab at 08:00.
  • 2015-10-13: sampling spectro pH for lab at 08:00.
  • 2015-10-15: We decided to stop LOV and SNAPO-CO2 samplings
  • 2015-09-15: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 07:00 (done by Point B team).
  • 2015-09-08: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00.
  • 2015-09-01: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00
  • 2015-08-25: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00 (done by Point B team).
  • 2015-08-11: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 07:00 (done by Point B team).
  • 2015-08-04: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00.
  • 2015-07-28: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00
  • 2015-07-21: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 06:44 (done by Point B team).
  • 2015-07-15: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 07:15 (done by Point B team).
  • 2015-07-06: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00.
  • 2015-06-30: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00.
  • 2015-06-22: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00.
  • 2015-06-16: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00.
  • 2015-06-09: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 12:00.
  • 2015-06-01: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00.
  • 2015-05-26: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:00.
  • 2015-05-19: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:00.
  • 2015-05-12: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 06:15.
  • 2015-05-05: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-04-21: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:20.
  • 2015-03-31: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 07:00.
  • 2015-03-24: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-03-17: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-03-03: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 09:00.
  • 2015-02-24: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 10:00.
  • 2015-02-24: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-02-10: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-02-03: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 09:00.
  • 2015-01-27: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2015-01-20: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 09:05.
  • 2015-01-12: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectro pH for lab at 08:20.
  • 2015-01-06: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:10.
  • 2014-12-22: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:20.
  • 2014-12-19: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:30.
  • 2014-12-09: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab at 08:20 (done by Point B team). No spectro pH sample.
  • 2014-12-02: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 08:20.
  • 2014-11-20: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2014-10-29: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 09:00.
  • 2014-10-14: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 07:00.
  • 2014-09-30: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 + lab and spectro pH for lab at 07:00.
  • 2014-09-15: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and spectrophotometric pH for lab measurements.
  • 2014-09-02: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) for SNAPO-CO2 at 08:00.
  • 2014-07-30: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and pH for lab analysis at 08:00.
  • 2014-07-16: sampling \(C_\mathrm{T}\), \(A_\mathrm{T}\) and pH for lab analysis at 08:00.

pH spectro measurements

Purified meta Cresol (mCresol) purple powder was bought from Robert Byrne (University of south Florida, FL, rhbyrne@usf.edu). Since November 2017, pure mCresol is supply by Fluidion (France, Dan Angelescu, d.angelescu@fluidion.com). The resulting prepared dye is used to measure pH by spectrophotometric method. We also used the dye on TRIS buffer bought from Andrew Dickson (salinity 35, Reference material for oceanic CO2 measurements from Scripps Institute of Oceanography, San Diego, CA, co2crms@ucsd.edu) at different times (just after preparation of the dye batch and after several months when the batch dye is almost finished) to check the precision of our measurments. We used TRIS from Batch 26. Here some TRIS pH results:

  • Batch 1 (new solution, 2014-05-14), TRIS pH measurement is 8.1715 (n = 3, sd = 0.002, measured temperature = 22.3°). Theoretical TRIS pH is 8.1853 at T = 22.3° and S = 38.
  • Batch 2 (new solution, 2015-03-18), TRIS pH measurement is 8.1828 (n = 2, sd = 0.014, measured temperature = 22.0°). Theoretical TRIS pH is 8.1879 at T = 22.0° and S = 35.
  • Batch 3 (new solution, 2015-04-21), TRIS pH measurement is 8.1894 (n = 3, sd = 0.006, measured temperature = 22.1°). Theoretical TRIS pH is 8.1848 at T = 22.1° and S = 35.
  • Batch 3 (old solution, 2015-10-21), TRIS pH measurement is 8.1899 (n = 2, sd = 0.003, measured temperature = 22.1°). Theoretical TRIS pH is 8.1848 at T = 22.1° and S = 35.
  • Batch 4 (newly prepared, 2015-10-21), TRIS pH measurement is 8.1864 (n = 2, sd = 0.006, measured temperature = 22.1°). Theoretical TRIS pH is 8.1848 at T = 22.1° and S = 35.
  • Batch 5 (newly prepared, 2016-08-22), TRIS pH measurement is 8.1821 (n = 7, sd = 0.003, measured temperature = 22.4°). Theoretical TRIS pH is 8.1753 at T = 22.4° and S = 35.
  • Batch 5 (old solution, 2017-03-23), TRIS pH measurement is 8.1772 (n = 2, sd = 0.008, measured temperature = 22.2°). Theoretical TRIS pH is 8.1816 at T = 22.2° and S = 35.
  • Batch 6 (newly prepared, 2017-03-23), TRIS pH measurement is 8.1974 (n = 2, sd = 0.005, measured temperature = 21.9°). Theoretical TRIS pH is 8.1910 at T = 21.9° and S = 35.
  • Batch 6 (old solution, 2017-11-21), no measurement because of contamination of the left dyr solution with acidic seawater.
  • Batch 7 (newly prepared, 2017-11-21), TRIS pH measurement is 8.1615 (n = 2, sd = 0.008, measured temperature = 22.4°). Theoretical TRIS pH is 8.1753 at T = 22.4° and S = 35.
  • Batch 7 (newly prepared #2, 2017-11-21), TRIS pH measurement is 8.1738 (n = 2, sd = 0.009, measured temperature = 22.2°). Theoretical TRIS pH is 8.1816 at T = 22.2° and S = 35.

Cary60 is now used: - Batch 7 (old solution, 2018-08-16), TRIS pH measurement is 8.1194 (n = 2, sd = 0.007, measured temperature = 24.2°). Theoretical TRIS pH is 8.1186 at T = 24.2° and S = 35. - Batch 8 (newly prepared, 2018-08-16), TRIS pH measurement is 8.1278 (n = 2, sd = 0.000, measured temperature = 23.9°). Theoretical TRIS pH is 8.1280 at T = 23.9° and S = 35.

Data processing

The last Markdown document “seafet_pointB_report_DATE.Rmd”:

  • reads the 2 months raw datafiles downloaded from seaFET sensor.
  • creates a new file with the right date format and useful columns of the 2 months period.
  • reads the file “pb_data/all_data/Data_DIC.csv” in order to add salinity, temperature, \(A_\mathrm{T}\), \(C_\mathrm{T}\) and nutrients from Point B. This file must be updated from the weekly measurements of salinity and temperature Point B data. Note that those parameters, taken each tuesday from Point B, are weekly interpolated. Measurements of \(A_\mathrm{T}\), \(C_\mathrm{T}\) and nutrients are updated every 6 months after analysis.
  • reads the file “spectro.csv” in order to add discrete pH data.
  • correct pH spectro measurement from lab temperature to in situ temperature.
  • correct pH seaFET data with spectro pH measurements according to Bresnahan et al. (2014), see Calibration of seaFET pH.

Calibration of seaFET pH

To calibrate the seaFET pH we use the approach described by Bresnahan et al. (2014). We used the 2 functions (“calib” and “calc”) that are reported in this paper. This approach was checked with the help of Yui Takeshita from Scripps Institute of Oceanography, San Diego, CA (ytakeshi@ucsd.edu). The final pH spectro and pH calculated from \(A_\mathrm{T}\) and \(C_\mathrm{T}\) values are normalized with the seaFET temperature in order to compare them with the final corrected seaFET pH value.

Results

Raw Continuous measurements

Graphic below shows raw pH and voltages (V) data for internal and external reference electrodes and temperature from the sensor. It also shows temperature from the sensor.

Discrete sampling

Graphic and table below show all the weekly interpolated Point B parameters (salinity, temperature, \(A_\mathrm{T}\) and \(C_\mathrm{T}\), phosphate and silicate).Note that:

  • NAs are related to Non Available data because of the in progress deployement, samples not yet measured or problem with measurements.
## Warning: Removed 414 rows containing missing values (geom_point).

date Chla_ptb deployment S_ptb T_ptb at_ptb dic_ptb PO4_ptb
2014-07-16 08:00:08 0.20753 5 37.91247 23.45153 2562.796 2236.734 0.000
2014-07-30 08:00:08 0.12000 5 38.06000 23.45000 2557.950 2233.150 0.289
2014-09-15 08:00:08 0.10000 5 38.18000 23.69000 2564.350 2240.300 0.057
2014-09-30 07:00:08 0.19000 6 38.19600 22.92448 2562.796 2231.143 0.000
2014-10-14 07:00:08 0.19000 6 38.18500 22.74490 2563.800 2236.450 0.026
2014-10-29 09:00:08 0.18000 6 38.17400 21.42250 2566.850 2232.700 0.026
2014-11-20 09:00:08 0.23800 6 37.77100 19.26738 2562.796 2228.120 0.000
2014-12-02 08:00:08 0.24000 7 37.28100 17.97840 2527.550 2223.600 0.045
2014-12-09 08:00:08 0.18000 7 37.69500 17.70860 2544.350 2235.450 0.037
2014-12-19 09:00:08 0.29521 7 37.84126 17.54203 2562.796 2237.555 0.000
2015-01-06 08:00:08 0.40000 8 37.94300 16.11770 2550.950 2236.800 0.037
2015-01-12 08:00:08 0.32000 8 37.96300 15.77570 2547.100 2247.650 0.028
2015-01-20 09:00:08 0.21000 8 37.97400 15.38060 2550.550 2252.050 0.039
2015-01-27 09:00:08 0.33000 8 37.98600 14.89900 2541.500 2242.800 0.044
2015-02-03 09:00:08 0.22000 8 38.04400 14.43360 2554.700 2261.700 0.048
2015-02-10 09:00:08 0.26000 8 38.06000 13.96880 2555.400 2263.050 0.058
2015-02-24 10:00:08 0.39000 8 37.90700 13.74010 2555.450 2261.050 0.057
2015-03-03 09:00:08 0.17000 8 38.00500 13.95550 2561.900 2262.400 0.046
2015-04-21 08:00:08 0.21000 9 37.74820 15.92710 2547.550 2258.650 0.030
2015-05-05 09:00:08 0.22000 9 37.70850 16.89340 2548.950 2250.600 0.032
2015-05-12 06:00:08 0.26000 9 37.60620 18.89190 2550.750 2253.700 0.049
2015-05-19 06:00:08 0.28000 9 37.48390 18.50620 2550.050 2258.400 0.055
2015-05-26 08:00:08 0.23000 9 37.80990 19.10510 2555.000 2243.250 0.047
2015-06-01 08:00:08 0.21159 9 37.76535 20.14632 2562.796 2256.827 0.000
2015-06-09 12:00:08 0.15000 10 37.79810 21.51620 2547.550 2250.800 0.048
2015-06-16 08:00:08 0.27000 10 37.77360 22.85610 2550.750 2241.250 0.049
2015-06-22 08:00:08 0.19000 10 37.64940 23.86710 2554.900 2242.250 0.029
2015-06-30 08:00:08 NA NA NA NA NA NA NA
2015-07-06 08:00:08 NA NA NA NA NA NA NA
2015-07-15 08:00:08 0.01700 11 38.06800 27.48700 2557.800 2249.200 0.000
2015-07-21 08:00:08 0.15000 11 38.11650 27.78320 2555.550 2237.450 0.000
2015-07-28 08:00:08 0.10000 11 38.13050 25.94730 2555.000 2232.700 0.000
2015-08-04 08:00:08 0.04000 11 38.20470 26.79170 2565.600 2240.650 0.000
2015-08-11 08:00:08 0.10000 11 38.16100 26.09300 2558.350 2230.750 0.051
2015-08-25 08:00:08 0.13000 11 38.22800 24.94210 2564.250 2231.250 0.056
2015-09-01 08:00:08 0.07000 11 38.27600 25.72720 2564.200 2226.700 0.040
2015-09-08 08:00:08 0.16000 11 38.27900 24.03090 2565.600 2228.200 0.034
2015-09-15 08:00:08 0.21900 11 38.29100 23.68130 2566.000 2226.600 0.086
2015-09-22 08:00:08 0.12700 11 38.28600 23.06920 2566.100 2233.500 0.047
2015-09-29 09:00:08 0.19400 11 38.36800 21.99800 2568.500 2228.000 0.045
2015-10-06 08:00:08 0.29000 12 38.10800 20.62870 2561.000 2225.950 0.055
2015-10-13 08:00:08 0.35000 12 38.13300 20.43780 2570.850 2232.850 0.051
2015-10-20 08:00:08 0.18000 12 38.35000 20.16280 2568.600 2236.000 0.078
2015-10-27 09:00:08 0.17000 12 38.35200 19.49840 2572.150 2240.500 0.080
2015-11-03 09:00:08 0.30000 12 38.29700 18.48330 2568.700 2237.300 0.041
2015-11-10 09:00:08 0.32000 12 38.19700 18.24460 2567.300 2241.350 0.039
2015-12-08 09:00:08 0.23000 12 38.24400 17.01460 2571.400 2245.300 0.044
2015-12-15 09:00:08 0.25781 13 38.22900 16.45820 2580.900 2260.900 0.035
2015-12-22 09:00:08 0.28000 13 38.21900 16.36790 2562.450 2240.900 0.022
2016-01-05 09:00:08 0.30100 13 38.20900 15.62280 2557.400 2244.900 0.056
2016-01-19 08:00:08 0.24000 14 38.22100 14.41970 2558.750 2255.700 0.093
2016-01-26 08:00:08 0.17000 14 38.20700 14.27640 2562.650 2261.600 0.051
2016-02-02 09:00:08 1.46000 14 38.14600 14.18710 2573.050 2287.250 0.073
2016-02-09 09:00:08 0.08000 14 38.16200 14.01240 2574.050 2285.750 0.063
2016-02-16 08:00:08 0.04000 14 38.19800 13.89310 2574.900 2289.800 0.094
2016-02-23 08:00:08 0.05000 14 38.16700 13.82730 2578.000 2294.600 0.068
2016-03-01 09:00:08 0.07800 14 37.85100 13.48750 2563.700 2267.650 0.078
2016-03-08 10:00:08 NA NA NA NA NA NA NA
2016-03-15 08:00:08 0.02100 15 37.91700 13.56800 2571.050 2295.400 0.069
2016-03-22 08:00:08 0.48000 15 37.81600 13.77780 2569.100 2292.700 0.000
2016-03-29 06:00:08 1.24000 15 37.86000 14.10170 2586.700 2289.800 0.160
2016-04-05 07:00:08 0.28800 15 38.00800 14.51300 2576.950 2286.550 0.000
2016-04-08 08:00:08 0.23559 15 37.97941 14.93367 2562.796 2281.732 0.000
2016-04-12 08:00:08 0.18900 16 37.95400 15.30760 2575.650 2277.450 0.100
2016-04-19 07:00:08 0.09200 16 37.90100 15.99820 2579.350 2281.700 0.060
2016-04-25 08:00:08 0.32400 16 38.00700 15.96940 2579.750 2283.000 0.060
2016-05-03 07:00:08 0.16000 16 38.09900 15.82040 2577.500 2279.850 0.070
2016-05-10 07:00:08 0.19900 16 38.04950 16.45110 2570.950 2275.050 0.060
2016-05-17 07:00:08 0.40900 16 38.04300 17.89430 2567.100 2278.750 0.050
2016-05-24 07:00:08 0.22800 16 38.07100 17.25540 2560.000 2258.250 0.100
2016-06-01 07:00:08 0.27400 16 38.07700 17.56040 2560.300 2266.800 0.080
2016-06-03 07:00:08 0.25400 16 38.05903 18.74655 2562.796 2273.397 0.080
2016-06-07 07:00:08 0.25400 17 38.03600 20.26630 2566.700 2281.850 0.080
2016-06-14 07:00:08 0.22200 17 37.94500 21.71140 2567.050 2277.450 0.060
2016-06-21 07:00:08 0.16700 17 37.97000 18.91100 2565.300 2262.450 0.070
2016-06-28 07:00:08 0.16700 17 37.99300 22.84030 2563.000 2260.300 0.070
2016-07-05 06:00:08 NA NA NA NA NA NA NA
2016-07-06 09:00:08 NA NA NA NA NA NA NA
2016-07-12 08:00:08 0.41000 18 38.08600 26.45750 2573.000 2253.700 0.120
2016-07-19 07:00:08 0.14800 18 38.16700 22.52540 2560.650 2257.650 0.100
2016-07-26 07:00:08 0.20300 18 38.24300 24.15770 2571.250 2262.050 0.070
2016-08-02 09:00:08 0.32500 18 38.26050 25.73360 2582.950 2271.050 0.100
2016-08-16 07:00:08 0.27200 18 38.25190 25.16610 2566.700 2253.050 0.100
2016-08-23 07:00:08 0.15100 18 38.37010 24.95860 2571.300 2258.550 0.030
2016-08-31 07:00:08 0.23000 18 38.31910 25.40210 2571.250 2262.750 0.050
2016-09-06 08:00:08 0.30200 18 38.32830 25.58070 2574.400 2261.550 0.040
2016-09-13 08:00:08 0.24000 19 38.08930 24.87360 2572.250 2250.000 0.020
2016-09-20 08:00:08 0.16600 19 38.29660 23.38480 2562.050 2239.700 0.040
2016-09-27 07:00:08 0.17100 19 38.21630 23.42840 2572.550 2241.550 0.050
2016-10-04 08:00:08 0.16100 19 38.29500 22.31150 2575.900 2247.700 0.030
2016-10-11 08:00:08 0.20100 19 38.27740 21.65380 2563.850 2232.950 0.030
2016-10-18 07:00:08 0.24100 19 38.26850 20.82800 2574.700 2265.800 0.030
2016-10-26 08:00:08 0.28000 19 38.23980 20.27040 2555.650 2239.500 0.088
2016-11-02 08:00:08 0.36000 20 38.19150 19.35700 2557.100 2236.200 0.105
2016-11-08 09:00:08 0.32000 20 38.09080 16.55220 2558.350 2275.600 0.073
2016-11-15 08:00:08 0.34000 21 38.22470 17.92690 2568.900 2248.200 0.077
2016-11-22 08:00:08 0.58000 21 38.19140 17.28080 2567.300 2259.850 0.081
2016-11-30 08:00:08 0.22000 21 38.18040 17.39390 2564.850 2250.300 0.053
2016-12-06 08:00:08 0.27000 21 38.20200 17.03800 2566.050 2254.750 0.050
2016-12-07 09:00:08 0.26000 21 38.19713 16.93799 2562.796 2255.048 0.000
2016-12-13 08:00:08 0.26000 22 38.18320 16.65160 2565.400 2255.900 0.040
2016-12-21 08:00:08 0.31000 22 38.19630 16.24400 2566.350 2258.750 0.040
2017-01-03 08:00:08 0.31672 22 38.12440 15.67410 2562.250 2252.750 0.040
2017-01-10 08:00:08 0.32302 22 38.15470 15.29420 2564.750 2261.350 0.030
2017-01-17 08:00:08 0.48059 22 38.16960 14.66060 2572.750 2274.150 0.090
2017-01-24 08:00:08 0.24353 22 38.19870 14.13770 2564.900 2282.300 0.040
2017-01-31 08:00:08 0.29213 22 38.20310 13.91690 2570.650 2283.600 0.030
2017-02-01 09:00:08 0.32907 22 38.20437 13.90430 2562.796 2285.865 0.000
2017-02-07 09:00:08 0.43485 23 38.20800 13.86820 2564.850 2292.350 0.030
2017-02-14 09:00:08 0.62056 23 38.21260 13.72620 2567.650 2284.950 0.030
2017-02-21 09:00:08 0.85118 23 38.21980 13.80110 2569.100 2289.350 0.030
2017-03-01 09:00:08 0.33816 23 38.03900 13.65770 2566.600 2282.800 0.096
2017-03-07 08:00:08 0.33816 23 38.21380 13.71720 2590.300 2304.300 0.030
2017-03-14 08:00:08 0.48505 23 38.19940 14.11450 2564.200 2270.850 0.060
2017-03-22 09:00:08 0.23438 23 38.10721 14.58352 2562.796 2272.517 0.000
2017-03-28 07:00:08 0.35865 24 38.04510 14.38800 2567.350 2281.300 0.060
2017-04-04 08:00:08 0.14792 24 38.02880 14.59150 2559.050 2275.900 0.050
2017-04-11 08:00:08 0.28169 24 37.94340 16.19630 2560.850 2278.650 0.100
2017-04-25 07:00:08 0.35733 24 38.04440 15.95360 2589.400 2273.050 0.070
2017-05-02 08:00:08 0.37521 24 38.01440 15.87950 2547.150 2257.650 0.080
2017-05-09 07:00:08 0.21219 25 38.01870 16.63270 2556.100 2269.550 0.090
2017-05-16 07:00:08 0.21684 25 37.97170 17.52510 2551.800 2269.050 0.040
2017-05-23 07:00:08 0.27215 25 38.00840 19.43440 2556.950 2261.250 0.060
2017-05-30 07:00:08 0.24461 25 37.91310 21.26510 2556.250 2258.950 0.060
2017-06-20 07:00:08 NA NA NA NA NA NA NA
2017-06-27 07:00:08 NA NA NA NA NA NA NA
2017-07-04 07:00:08 NA NA NA NA NA NA NA
2017-07-11 07:00:08 NA NA NA NA NA NA NA
2017-07-18 07:00:08 NA NA NA NA NA NA NA
2017-07-25 07:00:08 NA NA NA NA NA NA NA
2017-08-01 07:00:08 NA NA NA NA NA NA NA
2017-08-07 07:00:08 NA NA NA NA NA NA NA
2017-08-23 07:00:08 NA NA NA NA NA NA NA
2017-08-28 08:00:08 NA NA NA NA NA NA NA
2017-09-05 07:00:08 0.11515 27 38.04280 21.41560 2547.350 2242.250 0.086
2017-09-13 07:00:08 0.14442 27 37.97320 22.08310 2557.300 2240.300 0.056
2017-09-15 08:00:08 0.14488 27 37.98441 22.01194 2562.796 2240.368 0.000
2017-09-26 08:00:08 NA NA NA NA NA NA NA
2017-10-03 08:00:08 NA NA NA NA NA NA NA
2017-10-10 08:00:08 NA NA NA NA NA NA NA
2017-10-17 08:00:08 NA NA NA NA NA NA NA
2017-10-24 08:00:08 NA NA NA NA NA NA NA
2017-10-31 08:00:08 0.18226 28 38.28270 19.53860 2572.200 2257.800 0.053
2017-11-07 09:00:08 0.23258 28 38.20970 18.87160 2563.450 2259.700 0.078
2017-11-14 08:00:08 0.43079 29 38.21590 17.75240 2587.700 2265.100 0.061
2017-11-21 08:00:08 0.31158 29 38.20190 16.99410 2553.150 2247.950 0.076
2017-11-28 09:00:08 0.29402 29 38.21210 16.83260 2556.200 2247.800 0.022
2017-11-30 09:00:08 0.28371 29 38.20884 16.57117 2562.796 2256.719 0.000
2017-12-04 08:00:05 0.27189 30 38.20510 16.27130 2559.000 2266.950 0.049
2017-12-13 08:00:05 0.29445 30 38.07930 15.09240 2605.700 2284.500 0.055
2017-12-19 08:00:05 0.39965 30 38.18860 14.62400 2563.200 2296.450 0.063
2018-01-02 09:00:05 0.44523 30 38.19273 14.29937 2562.796 2292.172 0.000
2018-01-03 08:00:05 0.44600 31 38.19280 14.29390 2568.700 2292.100 0.030
2018-01-10 08:00:05 0.54900 31 38.19590 13.83970 2562.400 2286.200 0.036
2018-01-18 08:00:05 0.42300 31 38.24580 13.89720 2579.750 2302.300 1.422
2018-01-23 08:00:05 0.45900 31 38.27050 13.89500 2573.750 2307.200 0.077
2018-01-30 08:00:05 0.41200 31 38.27100 13.83140 2571.150 2294.450 0.056
2018-02-06 08:00:05 0.36214 31 38.30254 13.77167 2562.796 2298.333 0.000
2018-02-13 08:00:05 0.34100 32 38.33410 13.61940 2580.250 2306.150 0.093
2018-02-19 09:00:05 NA NA NA NA NA NA NA
2018-02-27 08:00:05 NA NA NA NA NA NA NA
2018-03-07 08:00:05 0.65400 33 38.26710 13.23540 2584.850 2312.300 0.076
2018-03-14 08:00:05 1.21900 33 37.63960 13.35840 2584.600 2305.900 0.051
2018-03-20 08:00:05 0.97900 33 37.58000 13.20400 2566.700 2288.450 0.078
2018-03-27 07:00:05 1.10900 33 37.80320 13.46640 2581.900 2292.750 0.077
2018-03-27 08:00:05 1.10900 33 37.80320 13.46640 2581.900 2292.750 0.077
2018-04-04 07:00:05 1.12000 34 38.09760 13.70560 2566.700 2293.800 0.082
2018-04-17 07:00:05 0.70900 34 38.15460 14.62830 2584.300 2302.950 0.084
2018-04-24 07:00:05 NA NA NA NA NA NA NA
2018-05-02 08:00:05 NA NA NA NA NA NA NA
2018-05-07 08:00:05 NA NA NA NA NA NA NA
2018-05-14 07:00:05 NA NA NA NA NA NA NA
2018-05-22 07:00:05 NA NA NA NA NA NA NA
2018-05-29 07:00:05 NA NA NA NA NA NA NA
2018-06-04 07:00:05 NA NA NA NA NA NA NA
2018-06-04 08:00:05 NA NA NA NA NA NA NA
2018-06-12 08:00:05 NA NA NA NA NA NA NA
2018-09-17 08:00:00 0.00000 35 38.16530 25.31490 2562.796 2278.350 0.000
2018-09-26 08:00:00 0.00000 36 38.40760 24.73100 2562.796 2278.350 0.000
2018-10-02 07:00:00 0.00000 36 38.38870 23.22700 2562.796 2278.350 0.000
2018-10-09 07:00:00 0.00000 36 38.35480 22.07970 2562.796 2278.350 0.000
2018-10-16 07:00:00 0.00000 36 38.33270 21.55910 2562.796 2278.350 0.000
2018-10-23 07:00:00 0.00000 36 38.27580 21.00050 2562.796 2278.350 0.000
2018-11-06 08:00:00 NA NA NA NA NA NA NA
2018-11-13 08:00:00 0.00000 37 38.02210 20.02000 2562.796 2278.350 0.000
2018-11-13 08:00:00 0.00000 37 38.02210 20.02000 2562.796 2278.350 0.000
2018-11-20 08:00:00 0.00000 37 38.05105 20.02000 2562.796 2278.350 0.000
2018-11-20 08:00:00 0.00000 37 38.05105 20.02000 2562.796 2278.350 0.000
2018-11-27 08:00:00 0.00000 37 38.08000 18.25000 2562.796 2278.350 0.000
2018-11-27 08:00:00 0.00000 37 38.08000 18.25000 2562.796 2278.350 0.000
2018-12-04 08:00:00 0.00000 37 38.10930 17.57270 2562.796 2278.350 0.000
2018-12-04 08:00:00 0.00000 37 38.10930 17.57270 2562.796 2278.350 0.000
2018-12-11 08:00:00 0.00000 37 38.10010 17.19460 2562.796 2278.350 0.000
2018-12-11 08:00:00 0.00000 37 38.10010 17.19460 2562.796 2278.350 0.000
2018-12-18 08:00:00 0.00000 37 38.07190 16.71470 2562.796 2278.350 0.000
2018-12-18 08:00:00 0.00000 37 38.07190 16.71470 2562.796 2278.350 0.000
2019-01-02 08:00:00 0.00000 37 38.06580 15.99600 2562.796 2278.350 0.000
2019-01-02 08:00:00 0.00000 37 38.06580 15.99600 2562.796 2278.350 0.000
2019-01-08 08:00:00 NA NA NA NA NA NA NA
2019-01-15 08:00:00 NA NA NA NA NA NA NA
2019-01-22 08:00:00 NA NA NA NA NA NA NA
2019-01-29 08:00:00 NA NA NA NA NA NA NA

seaFET T° vs Point B T°

Regressions are Model II (geometric).

Calibration of seaFET pH

Plots of E0ext25 and E0int25 returned by the function “pHCalib” are shown below. The mean values of E0ext25 and E0int25 (red and blue circles) are calculated by the “pHCalib” function for each period of deployement. Continuous measurements from April, the 12th to 31st are not shown because of the drift of the sensor due to biofouling.

Mail from Yui on the 2015-05-25:

Question to Yui: Data processing was performed as for the Arctic data. Both E0int and E0ext exhibit a trend with time. What do you suggest? Do I need to make a drift correction? If I do, how is this done?

Response: yes, there is a trend ,but look at the magnitude of the trend. it is small. The range of Eo_25C is ~2mV, which is actually quite good. The std. dev of Eo_25 is ~1mV, and since you’ve collected 17 samples, your uncertainty in your Eo_25 = stdev/sqrt(n), which is smaller than the uncertainty related to pH measurements (unpurified dye, K1/K2 uncertainty, etc). So I wouldn’t worry about applying a linear trend; it probably won’t matter anyways. but if you do decide to, just do a linear regression through the Eo_25C, and then use that function to calculate Eo_25 that you use to calculate pH.

We do not make any trend correction as advised by Yui (see above). In conclusion, we make the following calulations using the sensor’s pH INTERNAL refrerence.





Delta pH

Last calculated pH data, from TA/DIC point B (in grey), must not be taken in consideration since the last analysis are not done by SNAPO. Here, last data are calculated on a “mean TA/DIC” basis and do not reflect the reality.

McLaughlin et al. 2017

“operator error appears to be a defining factor in generating usable data with an ISFET sensor.” “differences between calibrated sensor pH values and values obtained from discrete, check samples can be expected to be as small as 0.02 pH units, and perhaps less.” “co-deployment of at least one other independent sensor would provide confirmation that the sensors are not drifting and greatly improve confidence in data quality.”

Article

seaFET pH15° vs calculated pH15°

Red circles are considered as outliers and are not taken into consideration for the regression parameters. We do not calculate pH after the 2015-08-04 because \(A_\mathrm{T}\) and \(C_\mathrm{T}\) data from Point B are not still available.




seaFET pH15° vs spectro15°





spectro15° vs calculated pH15°





Comparaison between EOL and Point B pH

## RMA was not requested: it will not be computed.

Linear regression was done on EOL and Point B pH data. EOL samples were mostly collected by the Point B team and mostly analysed right after by Samir Alliouane. Point B samples were all collected by the Point B team and analysed right after by Hortense De Lary.

pH INT - pH EXT

Final pH results

Maintenance

Following are dates and times (in UTC) for every lowering and recovery (deployement period) of the sensor. Changement of batteries and any other problems are also added here:

  • 2019-01-07: out of water at 09:10 and back in water at 10:30
  • 2018-11-09: back in water at 09:30.
  • 2018-10-25: out of water at 08:00 to give to Christophe for “science card” settings.
  • 2018-09-27: checking the magnet underwater for green light.
  • 2018-09-17: out of water for checking only (08:00) and put back 15 min after.
  • 2018-09-11: back in water at 12:00, New #1005 V2 model.
  • 2018-05-02: out of water for checking only (08:15) in situ and put back 15 min after.
  • 2018-03-27: out of water for checking only (08:10) in situ and put back 15 min after.
  • 2018-02-27: out of water at 09:10 and back in water at 10:30 (The external reference electrode was polished, battery was replaced). No measurements since 2018-02-16 15:00 (11 days).
  • 2018-01-02: out of water for checking only at lab and put back 25 min after.
  • 2017-11-30: out of water at 09:10 and put the other sensor #057 in water at 09:30 (The external reference electrode was polished).
  • 2017-11-07: out of water for checking only on board and put back 5 min after.
  • 2017-10-17: out of water at 09:10 and put back in water at 09:30 (The external reference electrode was polished).
  • 2017-09-15: out of water at 08:05 and back in water at 12:30 (The external reference electrode was polished).
  • 2017-08-29: out of water at 08:05 and back in water at 12:00 (The external reference electrode was polished).
  • 2017-06-14: out of water at 08:05 and back in water at 12:00 (The external reference electrode was polished, battery was replaced).
  • 2017-05-02:out of water at 08:05 and back in water at 12:00 on the 2017-05-03 because of bad weather (The external reference electrode was polished).
  • 2017-03-22:out of water at 09:05 and back in water at 14:00 (The external reference electrode was polished).
  • 2017-02-01:out of water at 09:05 and back in water at 14:00 (The external reference electrode was polished).
  • 2016-12-07:out of water at 09:20 and back in water at 14:00 (The external reference electrode was polished, battery was replaced).
  • 2016-11-08:out of water at 09:20 and back in water at 13:00 (The external reference electrode was polished).
  • 2016-10-26:out of water at 08:00 and back in water at 13:00 (The external reference electrode was polished).
  • 2016-09-06:out of water at 08:20 and back in water at 13:00 (The external reference electrode was polished).
  • 2016-07-06:out of water at 08:20 and back in water at 13:00 (The external reference electrode was polished, battery was replaced). No measurements since 2016-07-03 19:00 (3 days).
  • 2016-06-03:out of water at 08:20 and back in water at 13:00 (The external reference electrode was polished).
  • 2016-04-08:out of water at 08:20 and back in water at 13:00 (The external reference electrode was polished).
  • 2016-03-08:out of water at 10:50 and back in water at 14:00 (The external reference electrode was polished).
  • 2016-01-15:Back in water at 09:30 (No measurement during 8 days because of bad weather).
  • 2016-01-07:out of water at 09:30 and battery replacement (The external reference electrode was polished).
  • 2015-12-08:out of water at 09:30 and back in water at 13:30 (The external reference electrode was polished).
  • 2015-09-29:out of water at 09:10 and back in water at 13:00
  • 2015-07-27:sensor was switched up and down at 08:15 in order to put sensor toward the bottom as noted in the manual.
  • 2015-07-06:out of water at 08:10 and back in water at 12:30
  • 2015-06-27:out of battery at 02:00 (No more measurements during 10 days).
  • 2015-06-01:out of water at 08:20 and back in water at 13:10.
  • 2015-03-31:out of water at 07:10 and back in water at 13:10.
  • 2015-03-12 to 2015-04-02 :biofouling. Data not taken in consideration.
  • 2014-12-19:out of water at 09:30 and back in water at 12:30 and battery replacement.
  • 2014-11-20:out of water at 09:30 and back in water at 15:00.
  • 2014-09-16:out of water at 08:00 and back in water at 13:00.
  • 2014-06-27:out of water at 10:00, back in water at 11:00 and battery replacement.
  • 2014-06-05:out of battery at 11:00 (No more measurements during 22 days).
  • 2014-04-29:back in water at 17:00 (Not put before because of the bad weather).
  • 2014-04-28:out of water at 13:00.
  • 2014-02-11:out of water at 09:00 and back in water at 10:00.
  • 2014-01-07: out of water at 09:00 and back in water at 11:00.
  • 2013-12-18: sensor #007 installed.

EOL Buoy cleaning dates:

  • 2016-04-22:finished at 09:00

Acknowlegments

The sailors: J.-Y Carval, J.-L Prevost, P. Cohen.

Point B team: L. Mousseau, F. Petit, O. Passafiume, M. Durozier, A.-M. Corre, H. De Lary.

EOL buoy engineer: J.-M Grisoni.

Divers: G. De Liège, D. Luquet.

Bibliographic references

Robbins L. L., Wynn J. G., Lisle J. T., Yates K. K., Knorr P. O., Byrne R. H., Liu X., Patsavas M. C., Azetsu-Scott K. & Takahashi T., 2013. Baseline monitoring of the Western Arctic Ocean estimates 20% of Canadian Basin surface waters are undersaturated with respect to aragonite. PLoS ONE 8:e73796.

Dickson A. G. & Riley J. P., 1979. The estimation of acid dissociation constants in seawater media from potentiometric titrations with strong base. I. The ionic product of water. Marine Chemistry 7:89-99.

Dickson A. G., 1990. Standard potential of the reaction: AgCI(s) + 1/2H2(g) = Ag(s) + HCI(aq), and the standard acidity constant of the ion HSO4 in synthetic sea water from 273.15 to 318.15 K. Journal of Chemical Thermodynamics 22:113-127.

Dickson A. G., Sabine C. L. & Christian J. R., 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3:1-191.

DOE, 1994. Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. p. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory.

Edmond J. M., 1970. High precision determination of titration alkalinity and total carbon dioxide content of sea water by potentiometric titration. Deep-Sea Research 17:737-750.

Gattuso J.-P. & Lavigne H., 2009. Technical Note: Approaches and software tools to investigate the impact of ocean acidification. Biogeosciences 6:2121-2133.

Lee K., Kim T.-W., Byrne R. H., Millero F. J., Feely R. A. & Liu Y.-M., 2010. The universal ratio of boron to chlorinity for the North Pacific and North Atlantic oceans. Geochimica et Cosmochimica Acta 74:1801-1811.

Lueker T. J., Dickson A. G. & Keeling C. D., 2000. Ocean pCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for K1 and K2: validation based on laboratory measurements of CO2 in gas and seawater \(A_\mathrm{T}\) equilibrium. Marine Chemistry 70:105-119.

Perez F. F. & Fraga F., 1987. Association constant of fluoride and hydrogen ions in seawater. Marine Chemistry 21:161-168.